stowe



May 10, 1927. 1,627,871

Ll.. R. STOWE WATER 'I'UEIE EiDlLR Filed Aug, 19220 2 Sheetswheei l Patented May 10, 1927 alegran PATENT OFFICE.

LOYD R. STOWE, 0F ST. LOUIS, MISSOURI.

WATER TUBE BOILER.

Application led August 30, 1920. Serial No. 407,046.

This invention relates to water tube boilers, wherein banks of water circulating tubes are exposed to the products of combustion and communicate with drums or headers at their opposite ends; and it relates more particularly to the bank of tubes for the last or back pass of the boiler.

One of the principal objects of the. present invention is to increase the number of tubes in a bank and obtain a close spacing thereof, so as to obtain a greater heating surface and a more etiicient utilization of the products of combustion. Another object is to increase the number of tubes in a bank without weakening the shells, manifolds or headers in which the tubes terminate. Another object is to increase the rate of transfer of heat from the products of combustion to the water tubes. Another object of the close spacing of Lhe tubes is to divide the gases of combustion in small currents, thereby decreasing the distance between the center of the currents and the surfaces of the tubes and thus enabling a greater amount of heat to be extracted from the lnata-owcurrents of gas. Another object of'"'the close. spacing of the water tubes is to increase the. velocity of the products of combustion over the tubes. which increases the rate of heat transfer and also tends to prevent', accumulation of soot? and ashes on the surfaces of the water tubes, which accumulation retards the iow of gases and acts as a heat insulator.

The invention consists principally inthe arrangement of the water tubes which will permit of a close spacing of the tubes', thereby obtaining a greater efficiency in the transfer of the heat from the products of combustion to the water without weakening the drums into which the tubes are expanded and enabling t'ic drums to withstand higher pressures. The invention also consists in the combinations and arrangements of parts hereinafter described and clailned.

In the drawings. wherein like reference numerals refcr to like parts wherever they occur,

Fig. 1 is a central rex-tical section of a water tube boiler having a bank of water tubes in thc last pass thereof constructed in accordance. with the invention ang1 forming an economizer pass for the boiler;

Fig. 2 is a horizontal section through the last bank of tubes on the line-242 in Fig. 1, showing the arrangement of tube spacing.;

Fig. 3 is a detail View showing the tube arrangement in connection '.vith'an economizer;

Fig. 4 is a horizontal scctior. vion the line 4-4 in Fig. 3;

Fig. 5 is a diagrammatic view showing the opposite ends of the two setfI of tubes bent in opposite directions and expanded into headers; and l Fig. 6 is a View similar to Fig. 5 showing the upper and lower ends of alternate tubes bent in opposite directions and expanded into spaced upper and lower drums.

The water tube boiler shown in the accompanying drawings cofnp'ises a boiler setting 10, a furnace 11 having an automatic stoker 12 of the kind shown" in my application Serial No. 160912 tiled April 1917, patented Jan. 31. 1922, Patent. No. 1.405,072, arranged therein, an ignition arch 13 and a bridge wall 14 overhanging the rear end of the stoker. Banks of generating tubes 1:3 and 1G have their lower -ends expanded into a mnd drum 1T and have their-upper ends expanded into a steam and water drum 1S. the upper and lower ends of the banks` 1? and 16 being bent so as preferablyv to enter the drums 1T and 18 radially. The products of combustion from the furnace 11 are directed upwardly along;l the tubes of the front bank 15 by means ot'a batlie 19, which extends upwardl)l back bf said tubes from the mud drum 17 and-fterminates below the steam and water drum 17, leaving a passage between the upper-edge of the balile and the drum 1S. The baille 20 is located back of the second bank of tubes 16 and extends downwardly7 from the underside of the drum 18 to a point above the mud drum 17` thus leaving a passage etween its lower end and the top of th(` mu drum` Thus, the prod ucts of combustio, are directed upwardly from the furnace .12, across the top of the baille 1t). thence downwardly along the second bank of tubeS';` 16, and thence beneath titl the baille -G into the last or baci; pass 21 of the flue, which last pass communicates at its upper and with a smoke stack 22.

A third or rear bank of tubes, comprising tivo sets of tubes 2E and 24, is arranged in the baci( pass 2i. Both sets of tubes are disposed vertically in the last pass, the sets alternating and being arranged in parallel alinement for the greater portion ot their length. The upper ends oi' the tubes of the set 23 are expanded into the steam and Water drum 18, the tubes being bent forwardly so as to enter radially into said drum. The lower ends of the set of tubes 23 are expanded into the mud drum 17 and are also bent forwardly so as to enter radially into said drum. upper ends bent rearwardly and expanded into headers located near the outlet passage of the last pass. These headers are connected to the steam and water drum 18 by means of water pipes 26. The lower ends of the set of tubes 24 are extended downwardly below the mud drum 17 and are curved forwardly so as to enter radially into a. second and smaller mud drum 27, which is coiinected to the mud drum 1i" by means of a blow-otl` pipe 28. A series of bellies 29, which project toward 'cach other from the rear `wall of the furnace and from the rear of the bams 20 are arranged on opposite sides of the lest bank to cause the products of combustion in the last pass to travel alon the bank parallel with the tubes thereo This arrangement of ex ending the lower ends of the alternate tu es of the rows or sets of the rear bank into the two mud drums 17 and 2? in the lower portion of the boiler and ex ending the up er ends of the last bank a ternately into t e steam and Water drum 18 and the headers 25, results in a very close nesting of the straight parallel portions of the tubes and wide spacing of the bent ppi-tions thereof. The wide spacing of the ,nt ends of the tubes thus secured permits the distance between the tube holes in the drums to be increased; and as this distance limits the pressure that the drums are able to withstand, the increasing of this distance increases the strength of the drums. The loro spacing,r of the tubes is not important n tbe front banks, as the rst heat from the e is absorbed largely by radiation and, i erefore, the tubes pf the front banks may be spaced farther ap rt to enable the tubes to be replaced when b rnt out, due to the extreme heat to which they are subjected and to void obstructing the draft. As the products of combustion in the last pass move substantially parallel with the tubes, and as they have to pass in smell currents through the narrow spaces between the tubes, the velocity increased and the amount et heat transferred from the prodiicts of combustion to the tubes is increased thereby increing the The other set of tubes :24 have their,

amount of steam generated for e given amount of fuel consumed. This close nesting of the tubes and the balles 29, which cause the products of combustion to flow along the nested tubes, increases the velocity of the products of combustion over the sur faces of the tubes and tends to prevent the accumulation ot soot and ashes thereon.

Figs. 3 and 4 show the tube arrangement in connection with an economizer. In these figures, the upper and lower vends of alter nate tubes and 31 are bent in opposite directions and are expanded into spaced headers 32 which may be separate from each set of tubes or may be continuous. As shown in F ig. 4, the tubes of one set are disposed with their longitudinal centers opposite the spaces between the tubes on opposite sides thereof.

1n Fig. 5, the opposite ends of the tubes of one set 33 are shown bent in the same direction and expanded in the headers 34 and the opposite ends of the tubes 35 of the other set are bent in the same direction, but o posite to the bends of therst mentione set, and are expanded into headers 36 arranged opposite to the headers 34 of the first mentioned set.

In Fig. 6, the tubes of both sets 37 and 38 have their lowcr ends bent in opposite directions and expanded into drums 39 and have their upper ends bent.v across each other and expanded into drums 40 disposed on the side opposite from the headers into which the lower ends of the tubes are expanded.,

The foregoing described arrangements permit a close nestin of the tubes for a. greater portion of then' length, thus obtainmg a 'greater area of heating surfaces in a given space and also increasing the velocity of the products of combustion. The wide spacing of the ends of the nested tubes permits the tube holes in the drums to be placed farther apart and enables the drums to withstand greater pressures. y

The invention is not limited to boilers, but is equally adapted for use in connection with economizers, containers, superheaters, stills and similar apparatus.

What I claim is:

1. The combination`with a furnace and a tortuous flue therefor of a water tube boiler comprising upper and lower chambers and two banks 'bf generating tubes located in the first and second passes of said flue and connecting Said chambers, additional upper and lower chambers and a third bank of tubes disposed substantially vertically in the last pass, alternate tubes in said last pass being connected to said first mentioned chambers and the intermediate tubes being connected to said second mentioned chambers, said flue having battles in its last pass arranged to reduce the sectional area substantially below the sectional area of the iniirl tial pass whereby a relatively greater proortion of the products of combustion are iirought into contact with the tubes of the last pass, said upper chambers communieating with each other and said lower chambers communicating with each other.

2. A water tube boiler comprising pairs of upper and lower chambers, said upper chambers communicating with each other and said lower chambers communicating with each other, front, intermediate and rear banks of tubes connecting said chambers, and flue-forming walls separating said banks, the upper and lower ends of alternatc tubes of the rear bank communicating with one chamber each of the upper and lower pairs and the upper and lower ends of the remaining tubes of said rear bank communicating with the other chambers of said upper and lower pairs, the body portions of the tubes ofsaid rear bank being closely nested and their end portions being widely spaced at their points of communication with said chambers, and baflies arranged on opposite sides of said rear bank of tubes and stopping short thereof to cause the products of combustion to travel next to and substantially parallel to the body portion of said tubes.

3. A water tube boiler comprising a pair of steam and water chambers communicating with each other and a pair of mud chambers communicating with each other, front, intermediate and rear banks of tubes connecting the steam and water chambers with the 4mud chambers, the ends of alternate tubes of the rear bank communicating with one steam and wafer chamber ot a pair and with one mud chamber of a pair and the intervening tubes communicating with the other steam and water chamber of said pair and with the other mud Chamber of said pair, whereby a close neSting of the body portions of the tubes is obained and a wide spacing is obtained at their points of coinmunication with said steam and water-chambers and with said mud chambers.

4. The combination with a furnace and a tortuous flue therefor of a water tube boiler comprisingr upper and lower chambers connected by banks of generating tubes, a bank of vertically disposed parallel tubes located in the last pass of said boiler and leaving unoccupied a cross-sectional area substantially smaller than the unoccupied area of the preceding passes and communicating at their oiposite ends with chambers. the upper en s of alternate tubes comnnlnicating with one upper chamber and the lower ends of alternate tubes communicating with one lolwer chamber and the corresponding end.-` of the intervening tubes communicatinar with a different upper chamber and a different lower chamber, whereby a close nesting of the tubes is obtained along their middle portions and a wide spacing is obtained at their points of communication with said chambers, said upper chambers communicating with each other and said lowerchambers communicating with each other.

5. The combination with a furnace and a tortuous flue therefor of a water tube boiler comprising two upper chambers communicating with each other and two lower chambers communicating with cach other, banks of generating tubes in the first and second passes of said flue connecting one upper chamber and one lower chamber, a bank of vertically disposed parallel tubes located in the last pass of said fl'ue and communicating at their opposite endskwith upper and lower chambers, the upper ends of alternate tubes of the last pass communicating with one upper chamber and the upper ends of the intervening tubes communicating with the other upper chamber, and the lower ends of some of said tubes being connected to one of the lower chambers and the lower ends of the other tubes of said last pass being connected to the other of said lower chambers, said tubes being closely nested along their middle portions and being widely spaced at their points of communication with said chambers.

6.y The combination with a furnace and a tortuous flue therefor of a water tube boiler comprising pairs of communicating upper and lower chambers-connected by banks of generating tubes a bank of vertically disposed parallel tubes located in the last pass of said boiler and communicating at their op posite ends with chambers, the ends of alternate tubes of said bank communicating with one chamber and the corresponding ends of the remaining tubes of said bank communicating with a different chamber, the tubes of said bank being closely nested along their middle portions and being widely spaced at their points of communication with said chambers, and baflies arranged in the last pass of said boiler closc to and on opposite sides of said last mentioned bank of tubcs. to cause the products of combustion to travel substantially parallel and in contact with the major portions of said tubes.

7. The combination with a furnace and a tortuous flue haring a first pass. a second pass and a last pass therefor of a water tube boiler comprising,r upper and lower chambers connected by banks of generating tubes in the first and second passes of said flue. other upper and lower chambers and a bank of closely nested parallel tubes disposed vertically in thc last pass of said tiue and connectcd at their upper and lower ends with said last mentioned upper and lower chambers, said last mentioned chambers being in communication with said first mentioned chambers, the upper and lower ends of alternate tubes of said last mentioned bank communieating with said first mentioned upper and lower chambers, and the u per and lower ends of the-intermediate tu es of said last mentioned bank communicating with said last mentioned upper and lower chambers 1` whereby u close nesting of the tubes is obtained between their end portions and a wide spacing is obtained at their points of com "-the tubes being less than the unoccupied secl0 tional area of the earlier passes.

Signed at St. Louis, Missouri, this 31st day of July, 1920.

LOYD R. STOWE. 

